An interactive log for students and parents in my Pre-Cal 30S class. This ongoing dialogue is as rich as YOU make it. Visit often and post your comments freely.

Tuesday, December 13, 2005

Venn diagrams

Today we discuss about Venn Diagrams and how they were originally called Eulers circles. Then we started talking about how 6 is the first perfect number. Then we talked about how Euler had 11 children. But Sadly only 5 survive because of all the deceases back then. So anyways we started to take notes about sets.

set:a collection of objects may be things, people, numbers, etc....

subset: a "smaller" collection of objects taken from a given set.universe: the set of all objects being considered.null set: (A.K.A. the empty set) the empty set (it's got nothing in it) is a subset of every set. It is written as{O}.operation on sets:union (U) aUb means gather all the objects in set A with all the objects in set B.Union(U) means "or".

1 Comments:

BTW, Euler had 13 children, not 11 and the null set is not {0} (don't use a zero) it is {φ}. That's the greek letter phi. In order to get it to show up on your post write &PHI; (but don't use capital letters, use the lowercase letters phi.) It HAS to start with this & (shift-7) and end with a semicolon (;).